Wholly aromatic polyester resins long have been known. For instance, 4-hydroxybenzoic acid homopolymer and copolymers have been provided in the past and are commercially available. Those wholly aromatic polyesters normally encountered in the prior art have tended to be somewhat intractable in nature and to present substantial difficulties if one attempts to melt process the same while employing conventional melt processing procedures. Such polymers commonly are crystalline in nature, relatively high melting or possess a decomposition temperature which is below the melting point, and when molten frequency exhibit an isotropic melt phase. Molding techniques such as compression molding or sintering may be utilized with such materials; however, injection molding, melt spinning, etc., commonly have not been viable alternatives or when attempted commonly have been accomplished with difficulty.
Representative publications which discuss wholly aromatic polyesters include: (a) Polyesters of Hydroxybenzoic Acids, by Russell Gilkey and John R. Caldwell, J. of Applied Polymer Sci., Vol. II, Pages 198 to 202 (1959), (b) Polyarylates (Polyesters From Aromatic Dicarboxylic Acids and Bisphenols), by G. Bier, Polymer, Vol. 15, Pages 527 to 535 (August 1974), (c) Aromatic Polyester Plastics, by S. G. Cottis, Modern Plastics, Pages 62 to 63 (July 1975); and (d) Poly(p-Oxybenzoyl Systems): Homopolymer for Coatings: Copolymers for Compression and Injection Molding, By Roger S. Storm and Steven G. Cottis, Coatings Plast. Preprint, Vol. 34, No. 1, Pages 194 to 197 (April 1974). See also, U.S. Pat. Nos. 3,039,994; 3,169,121; 3,321,437; 3,553,167; 3,637,595; 3,651,014; 3,723,388; 3,759,870; 3,767,621; 3,778,410; 3,787,370; 3,790,528; 3,829,406; 3,890,256; and 3,975,487.
Also, it more recently has been disclosed that certain polyesters may be formed which exhibit melt anisotropy. See for instance, (a) Polyester X7G-A Self-Reinforced Thermoplastic, by W. J. Jackson Jr., H. F. Kuhfuss, and T. F. Gray Jr., 30th Anniversary Technical Conference, 1975 Reinforced Plastics/Composites Institute. The Society of the Plastics Industry, Inc., Section 17-D, Pages 1 to 4, (b) Belgian Pat. Nos. 828,935 and 828,936, (c) Dutch Pat. No. 7505551, (d) West German Nos. 2520819, 2520820, 2722120, 2834535, 2834536, and 2834537, (e) Japanese Nos. 43-223, 2132-116, 3017-692, and 3021-293, (f) U.S. Pat. Nos. 3,991,013; 3,991,014; 4,057,597; 4,066,620; 4,067,852; 4,075,262; 4,083,829; 4,118,372; 4,130,545; 4,130,702; 4,156,070; 4,159,365; 4,161,470; and 4,169,933; and (g) U.K. Application No. 2,002,404. See also commonly assigned U.S. Ser. Nos. 877,917, filed Feb. 15, 1978; (now U.S. Pat. No. 4,184,996) 17,007, filed Mar. 2, 1979; 21,050, filed Mar. 16, 1979; (now U.S. Pat. No. 422,433) 32,086, filed April 23, 1979; (now U.S. Pat. No. 4,219,461) and 54,049, filed July 2, 1979.
Additionally, see commonly assigned U.S. Ser. No. 10,392, filed Feb. 8, 1979 entited "Polyester of Para-Hydroxy Benzoic Acid, 1,2-Bis(Para Carboxy Phenoxy) Ethane, Terephthalic Acid and Substituted Hydroquinone Capable of Forming an Anisotropic Melt Which Readily Undergoes Melt Processing", and commonly assigned U.S. Ser. No. 10,393, filed Feb. 8, 1979, entitled "Polyester of Para-Hydroxy Benzoic Acid, 1,2-Bis(Para-Carboxyphenoxy)Ethane, Terephthalic Acid, and Hydroquinone Capable of Forming an Anisotropic Melt Which Readily Undergoes Melt Processing".
It is an object of the present invention to provide an improved melt processable wholly aromatic polyester which in at least some embodiments can be formed on a more economical basis than the polyesters of commonly assigned U.S. Ser. Nos. 10,392 and 10,393.
It is an object of the present invention to provide an improved melt processable wholly aromatic polyester which exhibits greater thermal stability, modulus and impact resistance than the polyesters of commonly assigned U.S. Ser. Nos. 10,392 and 10,393.
It is an object of the present invention to provide an improved wholly aromatic polyester which is suited for the formation of quality molded articles, melted extruded fibers, and melt extruded films.
It is an object of the present invention to provide an improved melt processable wholly aromatic polyester capable of forming an anisotropic melt phase at a temperature below approximately 400.degree. C., and preferably below approximately 360.degree. C.
It is an object of the present invention to provide an improved wholly aromatic polyester which forms a highly tractable melt phase.
It is an object of the present invention to provide an improved wholly aromatic polyester which forms an anisotropic melt phase at a temperature well below its decomposition temperature and which may form quality high performance fibers.
It is an object of the present invention to provide improved wholly aromatic polyester fibers which particularly are suited for use as fibrous reinforcement in a rubber matrix.
It is another object of the present invention to provide an improved wholly aromatic polyester which readily may be melt extruded to form a film.
It is another object of the present invention to provide an improved wholly aromatic polyester which readily may be injection molded to form a molded article (which optionally may be fiber reinforced).
These and other objects, as well as the scope, nature and utilization of the invention will be apparent to those skilled in the art from the following detailed description.